A power module is a power supply that can be directly mounted on a printed circuit board. It is characterized by supplying power to a dedicated integrated circuit, a digital signal processor, a microprocessor, a memory, a field programmable gate array, and other digital or analog loads. Generally, this type of module is referred to as a point-of-load power supply system or a point-of-use power supply system. A modular structure has a plurality of advantages. Therefore, a modular power supply is widely used in a switch device, an access device, mobile communications, microwave communications, optical transmission, a router, and the like in the communications field, and auto electronics, aeronautics and astronautics, and the like. A modular power supply has an isolation function, a strong anti-interference capability and its own protection function, and is easy to integrate. In an application scenario in which voltage conversion needs to be performed, a power module further includes an alternating current-direct current (AC-DC) converter or a direct current-direct current (DC-DC) converter.
A power module is relatively commonly used for various circuits. An existing direct-current voltage pre-regulator power supply applies an isolation function of the power module. Meanwhile, a power supply convertor or direct-current convertor is also applied to an architecture of such circuits.
However, the existing direct-current voltage pre-regulator power supply mainly adopts a completely-isolated circuit architecture and non-isolated completely-straight-through circuit architecture. A circuit structure that adopts the isolated architecture is complex, so that power supply output efficiency is low and precision of an output voltage is poor.